Thread chasing mechanism for automatic lathes



June 22, 1937. R. ECKARDT ET AL 2,084,893

THREAD CHASING MECHANISM FOR AUTOMATIC LATHES Filed Sept. 25, 1936 2 Sheets-Sheet 1 I E H 5 i L 1 e14- 4Q F V INVENTORS,

Fn-z'iz Nut/Ellen June 22, 1937. R. ECKARDT ET AL 2,084,898

THREAD CHASING MECHANISM FOR AUTOMATIC LATHES Filed Sept. 25, 1956 2 Sheets-Sheet 2' INVENTOR S,

Rcuio Edi'arvdii ET HnUEFc g) N raeumocfiaiuw RTTORNEY Patented June 22, 1937 UNITED STATES THREAD CHASING MECHANISM FOR AUTO- MATIC LATHES Rudolf Eckardt, Erich Huth, Fritz Miller, and

Richard Rahm, Leipzig, Germany, assignors to National Acme Company, Cleveland, Ohio. a

corporation of Ohio Application September-23, 1936, Serial No. 102,116 In Germany March 2, 1936 21 Claims.

This invention relates to thread chasing mechanism for automatic and turret lathes, the principal object of the invention being the provision of a mechanism which, by means of a changeable 5 gear transmission into reduced speed and by means of a cam member rotating at a lower speed than the driving shaft serves to engage the thread guiding die or master thread follower independently of the rotation of the master 10 thread gauge or pattern.

A further object of this invention is the provision of a mechanism which, when used for chasing multiple threads, provides for an .accurate automatic indexing so that each thread 5 may be chased individually and successively.

A furtherqobject of the invention is the provision of a mechanism or movement transmitting mechanism by which a too rapid disengagement of the thread guiding die from thegauge no pattern and the occurrence of hard impacts or shocks is prevented, such impacts as a rule being unavoidable with a quickly rotating pattern shaft thereby to provide a smootheroperation than is possible in machines in which the lifting of the thread guiding die is effected by means of cams carried by a gauge pattern shaft rotatingat relatively high speed. I

This invention, therefore, contemplates transmitting the movement from the gauge pattern 10 shaft by way of an interposed oscillating shaft thus avoiding shocks which are liable' to be caused by the impacts of rapidly rotating cams.

A further object of this invention is the provision of a mechanism in which the lifting or retum of the chaser or tool-carrying, quick acting slide is effected after each chasing operation by a semi-circular oscillating cam.

In the present improvement, a cam lever which is pivotally fastened to the longitudinal slide 40 establishes the starting position of the chaser for each new cutting phase. During the final phase of each return movement of the longitudinal slide, this lever engages upon ashort incline and being co-operatively associated in a certain manner with the tool carrying sliding support or slide, it forces the same back into its initial position.

It is known that thread cutting or chasing mechanisms for automatic and turret lathes are driven from the work carrying spindleat a ratio of 1 to 2 so as to make possible the chasing of threads having small pitch from a master thread gauge or pattern having' twice that pitch, this Y being desirable for the purpose of securing a satisfactory operating engagement or meshing between the master thread pattern and the asso- 4 ciated master thread guiding die or, follower. Theretofore, it has been customary to disengage the follower from the master thread by means of cams which rotate at the same speed as the master gauge shaft and it is also known to withdraw the tool or chaser from the finished work by means of cam curves and associated cam lever actuated from the control shaft of the machine.

This invention possesses other objects and features of advantage, some of which with the foregoing will be set forth in the following description. In the following description and in the claims, parts will be identified by specific meansfor convenience, but they are intended to be as the art will permit.

In the accompanying drawings there has been illustrated the best embodiment of the invention known to us, but such embodiment is to be regarded as typical only of many possible embodiments, and the invention is not to be limited thereto.

The novel features considered characteristic of this invention are set forth with particularity in the appended claims. The invention itself,

however, both -as to its organization and its method of operation, together with additional objects .andadvantages thereof, will best be understood from the following description of .a

specific embodiment when read in connection 7 V with the accompanying drawings in which Fig. 1 isv a front elevation of the novel thread chasing mechanism of an automatic lathe, parts sectioned according to section line A-B of Fig. 5 exposing the bearings of the starting rod and the thread-pattern shaft.

Fig. 2 is a top view of the device 'shown in Fig. 1.

Fig. 3 shows a cross section taken along the line C-D of Fig. 1, showing the supporting frame and a side view of theupper slide and viewed in the direction of the arrows P.

Fig. 4 is a cross section through the driving mechanism taken along the line E-F of Fig. 1, viewed in the direction of arrows R. The master thread pattern and the main control parts immediately associated therewith.

Fig. 5 is a cross section viewed in the direction of the arrows T of the gear box and taken along the line 11-1 of Fig. 1, showing the oscillating lever controlling the follower or thread guiding die arm and the controlling cam member therefor. It also shows the changeable gear transmission between the driving shaft and the thread 15 generic in their application to similar parts as v pattern shaft as viewed in the direction of the arrow U in Fig. 2.

Similar characters of reference indicate corresponding parts in the several views.

Before explaining in detail the present im provement and mode of operation thereof, we desire to have it understood that the invention is not limited to the details of construction and arrangement of parts illustrated in the accompanying drawings since the invention is capable of .other embodiments, and that the phraseolog'y which we employ is for the purpose of description and not of limitation.

In one embodiment as illustrated, the device comprises:

Firstly: Of a thread chasing or cutting mechanism comprising a primary or main slide or sliding support S operativelymounted upon the supporting frame for vertically controlled move- 2t and 22.

ment; a secondary or intermediate horizontally movable slide l operatively mounted and controlled upon the main slide S; and a quick-acting chaser carrying 'slide 2 preferably springurged in vertical direction upon the secondary slide l and carrying a tool carrier 3 and a thread cutting tool or chaser 3, and

Secondly: Of a gear box comprising a clutch mechanism 6, a master thread pattern ll, changeable gears 8, 9 and i5 which are selected and combined according to the pitch and the number of threads required. Further, the improvement 1 comprises a cam member H adjustably connected to the driven gear iii, an oscillating arm is having a roller l2, a guide arm Hi resiliently connected to the thread guiding die arm l5, a tiemember l6 rigidly connecting the oscillating shaft H with the feed rod 58, the latter through an adjustable spindle head it having operating consleeve fiaiw hich is operatively connected with a disengageable part 26 of the pattern shaft. This pattern carrying shaft, herein briefly termed the pattern shaft, consists of two parts 26 and 26a.

In order-to avoid high speed rotation of the shaft 26'26a and to insure smooth operation thereof, the transmission gears 2i and 22 are so selected that thenumber of rotations of the shaft 26-26a is one-half of the number of the rotations of the shaft 23. The thread pattern I therefore rotates at half the speed of thework carrying spindle of the machine and of the work 21. I

Hence, when cutting single threads, the pitch of the thread pattern I must be twice that of the work 2'0. The shaft portions 26-2611 being separable as at 2a, that is at a point between the gear 8 and the thread pattern I, it is possible to exchange the thread patterns after withdrawing the shaft portion 26. The changeable gear 8 being rigidly connected to the part 26 actuates the gear! and thereby the gear Ill. The gear 9 is shiftable by means of a fork 29. The gear Iii is loosely mounted on a running sleeve 39 carried by the housing! and the gear) is provided with the cam member ll hereinbefore referred to and is adjustable by means of a slot 3| and is fastened to the gear it] by a screw 32.

The gauge pattern and the gears 8 and Hi can. -be readily changed after the shaft portion 26a is withdrawn.

Shortly before the commencement of the thread chasing operation, that istosay when the chaser 4 and the cam-roller i2'of the oscillating lever l3 are in the dotted position, Fig. 5, and as soon as the chaser d due to the uniformly controlled progress of the sliding support S has been advanced the depth of a prospective cut, the cam it engages the roller E2 of the oscillating lever is, Fig. 5, which at this. moment occupies its lowered position andlifts same into the upper position shown in full lines in Fig. 5. The lever l3, the guide arm I l and the thread guiding die arm or follower arm 15, all of which are supported upon the shaft l1, are swung from the dotted position, Fig. 5, to the position shown in the same figure in full lines; the thread guiding die ita therefore meshes with the gauge pattern 7! and is held in this position during the chasing operation by the spring urged bolt Hia forming a movable front portion or telescoping head of the guide lever it, which bolt co-operates with-the adjustable guide Mb. The thread cutting or chasing operation proper now takes place due to the rotation of the thread pattern I causing the axial movement or displacement of the oscillating shaft 17' and along therewith through the tie member it of the feed rod [8 against the pressure of the coil spring 37. As soon as the lever head or bolt Ma slides off the stationary guide Mb (this position being shown in dotted lines. in Fig. 4) the thread guiding die I5a is withdrawn from the gauge pattern I by the action of the spring i512.

The oscillating movement of the lever it and thereby also of the lever 83 is limited by a stop plate H30 extending from the lever id and which, during the recoil of the arms 53, it and 55 engages itself upon the upper surface of the rail Mb. To ensure a proper and positive disengagement of the thread guiding die or thread follower member lEa, the. roll 55c carried by the lever i5 is caused to engage upon atapering rail i512. Immediately after thedie or follower fl5a has been disengaged the levers M and it as a slidable unit are driven back, that is to say, laterally displaced due to the attendant-release of the compressed spring 3'! so that the cam roller 92 again enters the operating range of the cam member ll.

' In order to prevent such minor irregularities as may be caused during the operating advance of the 'die from being transmitted to and in-. fluencing the accuracy of the thread chaser, and in order to obtain a smooth transmission from the thread pattern '1 to the feed rod It, a resilient connecting means such as a cushioning spring 33 is shown inserted between the die arm i5'and the guide lever H1.

The rate of feed of the die He is greater or smaller depending upon the adjusted effective length of the stationary guide Mb. For chasing short threads it is sufficient to select the gear ratio of the gears 8 and llland. the pitch of the pattern gauge 1 in'such a manner that after each rotation of the cam member H theo'scillating lever I3 is raised, whereupon the die 55a again meshes'with the thread pattern l. 4

When chasing long threads or threads with a small pitch the cam member H makes several rotations before the roller I: of. the lever I3 is again displaced'into the range of the cam member 'Il." When. chasing multiple' threads the change gears 8, 9, and I0 themselves are used as indexing mechanism. In this case the gear ratio and the number of the thread enterings of the gauge pattern I is to be selected in such a manner that the cam member II during the chasing operation is advanced relative to the prior.indexing position an angular distance required by the index ofthe. multiple screw 21.

- Corresponding to the number of thread enterings, the operating "phase of the die- I5a when actuated by the lever I3 is then relatively shifted or staggered with respect to the pattern 1 a num: ber of degrees which corresponds to the required index. For instance, for cutting a quintuple l5 thread, a quintuple thread pattern and change gears with and 44 teeth respectively should be selected.

The longitudinal displacement of the shaft IT is transmitted to the feed rod l8 by the tie- 20 member I6 so as to permit the shaft I1 to move the rod I8 engaging a T-shaped undercut groove of the secondary slide by means of an adjustable spindle head I9.

This secondary slide is advanced during the the direction of the arrow V, Fig. 2. as long as the upper guide rail 34 of the quick acting or tool holding slide'2 contacts with the outer periphery of the semi-circular cam 35, Fig. 1. But, as soon as the end of the guide rail 34 reaches the shoulder b of the cam 35, the slide 2 is drawn upward through the action of the springs 36 at the moment when the thread guiding die I5a is disengaged from the thread pattern I by the tension of the spring I51) and the stop rail I M.

The pressure of the spring 31 having been compressed by the chasing operation returns the feed rod I8 and the secondary slide I to their initial position. The guide rail 34 at its right hand edge portion engages the shoulder b of the oscillating cam 35, Fig. 1, returning the same to its initial position. At the same time the cam lever 39 pivoted at 38 to the slide I has its recessed portion or tooth travel over' a guide rail' 40 having a short incline 4| and adiustably fastened to the main sliding support S. However, before the oscillating lever I3 is again lifted by the cam'member I l, the tooth of the cam lever 39 has reached the incline 4| causing the cam lever end to press the tool carrying slide 2 downward,

thereby again bringing the chasing tool 4 into its operating position relative to the work 21. As soon as the thread is cut to its desired depth, the feed of the main sliding support S is limited due to a set screw 43 abutting against the portion S of the machine frame. The slide S'along with .the slides I and 2 is retracted in an upward direction through the customary cam member of the control shaft of the machine in a direction opposite to the arrow near S, Fig. 1.

Due to'the urge of the compressed spring 44 the rod 24 moves down the incline 23 of the main slide 8 and to'the left and thus disengages by means of the lever 25 and through theclutch actuating sleeve to, the clutch 6. The chasing I tool 4 remains inactive until, by the downward feed of the main slide S (direction of arrow near 8), the clutch is again thrown into engagement due to the displacement on the incline 23 of the thread chasing operation by the feed rod I8 in rod 24. The cutting operation above described rangement. it is not intended to limit the inven tion beyond the terms of the several claims or the requirements of the prior art.

ing slide mounted on said intermediate slide, a

pattern carrying clutch controlled shaft, means for rotating it, means operated by the main slide for controlling the clutch of said pattern shaft, an axially movable oscillating shaft, means carried by the oscillating shaft and co-operating with the pattern ofthe pattern carrying shaft for axially moving said oscillating shaft, means for oscillating said shaft, and a feed rod tied to saidoscillating shaft for horizontally shifting the intermediate slide and'thereby the chaser slide.

2. Thread chasing mechanism for automatic "lathes comprising a compound slide mechanism consisting of a vertically movable main slide, a horizontally movable intermediate slide mounted thereon and a vertically movable chaser. carrying slide mounted on said intermediate slide, a pattern carrying clutch controlled shaft, means for rotating it, means operated by the main slide for controlling the clutch of said pattern shaft, an axially movable oscillating shaft, means carried by the oscillating shaft and co-operating with the pattern of the pattern carrying shaft for axially moving said oscillating shaft, means for oscillating said shaft and.comprising cam controlled means, and a feed rod tied to said oscillating shaft for horizontally shifting the intermediateslide and thereby the chaserxslide.

3. Thread chasing mechanism for automatic lathes comprising a compound slide mechanism consisting of a vertically movable main slide, a horizontally movable intermediate slide mounted thereon and a vertically movable chaser carrying slide mounted on said intermediate slide, a pattern carrying clutch controlled shaft, means for rotating it, means operated by the main slide for controlling the clutch of said pattern shaft,

an axially movable oscillating shaft, means carried' by the oscillatingshaft and co-operating with-the pattern of the pattern carrying shaft for axiallymoving said oscillating shaft, means for oscillating'said shaft and comprising cam controlled means connected with the rotating means of the pattern shaft for effecting co-operation of the pattern and its co-operating means, and a feed rod tied to said oscillating shaft for horizontally'shifting the intermediate slide and thereby the chaser slide.

4. Thread chasing mechanism for automatic lathes comprising a compound slide mechanism consisting of a vertically movable main slide, a

horizontally movable intermediate slide mounted thereon and a vertically movable chaser carrying slide mounted on said intermediate slide, a pattern carrying clutch controlled shaft, means for rotating it, means operated by the main slide zontally shifting the intermediate slide and thereby the chaser slide, the organization being such that the pattern is rotated at half the speed of the work 5. Thread chasing mechanism for automatic lathes comprising a compound slide mechanism consisting of a vertically movable main slide, a horizontally movable intermediate slide mounted thereon. anda vertically movable chaser carrying slide mounted on said intermediate slide, a pattern carrying clutch controlled shaft, means for rotating it, means operatedbythe main slide for controlling the clutch of said pattern shaft,

an axially movable oscillating shaft, a threadguiding die carriedby the oscillating shaft and.

co-operating with the pattern of the pattern, carrying shaft for axially moving said oscillating shaft, cam means for'oscillating said shaft, and a feed rod tied to said oscillating shaft for horizontally shifting the intermediate slide and thereby the chaser slide, the pitch of the thread pattern being twice that of the work. I

6. Thread chasing mechanism for automatic lathes comprising a compound slide mechanism consisting of a vertically movable main slide,

.a horizontally movable intermediate slide mounted thereon and a vertically movable chaser carrying slide mounted on said intermediate slide, a pattern carrying clutch controlled shaft, means for rotating it, means operated by the main slide for controlling the clutch .of said pattern shaft,

consisting of a vertically movable main slide, a horizontally movable intermediate slide mounted thereon and a vertically movable chaser carrying slide mounted on said intermediate slide, a pattern carrying clutch controlled shaft, means for rotating it at a reduced speed, means operated by the main slide for controlling the clutch of said pattern shaft, an axially'movable oscillating shaft, means carried by the oscillating shaft I and co-operating with the pattern of the pattern carrying shaft for axially moving said oscillating shaft, means for oscillating said shaft, and a feed rodtied to said oscillating shaft for horizontally shifting the intermediate slide and thereby the chaser slide.

8. Thread chasing mechanism for automatic lathes comprising a compound slide mechanism consisting of a vertically movable main slide, a horizontally movable intermediate slide mounted thereon and a vertically movable chaser carry ing slide mounted on said intermediate slide, a

pattern carrying clutch controlled shaft, means for rotating it at half the speed of the i work, means operated by the main slide for controlling the clutch of said pattern shaft, an axially movable oscillating shaft, means carriedby the oscillating shaft and co-operating with the pattern of the pattern carrying shaft for axially moving said oscillating shaft, means for oscillating said shaft,

and a feed rod tied to said oscillating shaft for 2,084,898 a feed rod tiedto said oscillating shaft for hori- \7 horizontally shifting the intermediate slide and.

thereby the chaser slide.

9. Thread chasing mechanism for'automatic lathes comprising a vertically and horizontally movable slide mechanism carrying a chaser, a pattern carrying clutch controlled shaft, means for rotating it, means operated by the sliding mechanism for controlling the clutch of the pattern shaft, an axially, movable oscillating shaft, means operated by said oscillating shaft during its axial movement for horizontally shiftingthe means for oscillating said shaft at a predetermined time. 10. Thread chasing mechanism for automatic lathes comprising a vertically and horizontally its axial movement for horizontally shifting the slide mechanism and thereby the chaser, means carried by the oscillating shaft and co-operating' with the pattern of the pattern carrying shaft for axially moving said oscillating shaft, and means for oscillating said shaft at a predetermined time and. including cam means.

11. Thread chasing mechanismfor automatic lathes comprising a vertically and horizontally movable slide mechanism carrying a chaser, a

pattern carrying clutch controlled shaft, means for rotating it, means operatedby .the sliding mechanism for controlling the clutch of the pattern shaft, an axially movable oscillating shaft, means operated by said oscillating shaft during its axial movement for horizontally shifting the slide mechanism and thereby the chaser,

means carried by the oscillating shaft and (:0-

operating withthe pattern of the pattern carrying shaft for axially moving said oscillating shaft, means for oscillating said shaft at a predetermined time, and means for disengaging the chaser from the work and including means for controlling such disengagement at a predetermined time.

12. Thread chasing mechanism for automatic lathes comprising a vertically and horizontally movable slide mechanism carrying a. chaser, a pattern carrying clutch controlled shaft, means for rotating it, means operated by the sliding mechanism for controlling the clutch of the pattern shaft, an axially movable oscillating shaft, means operated by said oscillating shaft during its axial movement for horizontallyshifting the slide mechanism and thereby the chaser, means carried by the oscillating shaft and co-operating. with the pattern of the pattern carrying shaft foraxially moving said oscillating shaft, means for oscillating said shaft at a predetermined time,

and means for disengaging the chaser from the for rotating it, means operated-by the sliding mechanism for controlling'the clutch of the pattern shaft, an axially movable oscillating shaft, means operated by said oscillating shaft during its axial movement for horizontally shifting the slide mechanism and thereby the chaser, means carried by the oscillating shaft and co-operating with the pattern of the pattern carrying shaft for axially moving said oscillating shaft, means for oscillating said shaft at a predetermined time, and means for disengaging the chaser from the work and including means for controlling such disengagement at a predetermined time and comprising a semi-circular cam.

14. Thread chasing mechanism for automatic lathes comprising a compound slide mechanism consisting of a vertically movable main slide, a horizontally movable intermediate slide mounted thereon and a vertically movable chaser carrying slide mounted on said intermediate slide, a pattern carrying clutch controlled shaft, means for rotating it, means operated by the main slide for controlling the clutchof said pattern shaft, an axially movable oscillating shaft, means carried by the oscillating shaft and co-operating with the pattern of the pattern carryingshaft for axially moving said oscillating shaft, means for oscillating said shaft, a feed rod tied to said oscillating shaft for horizontally shifting the intermediate slide and thereby the chaser slide, and means carried by the main slide and contacting with the chaser slide for controlling the disengagement of the chaser from the work.

15. Thread chasing mechanism for automatic lathes comprising a compound slide mechanism consisting of a vertically movable main slide, a horizontally movable intermediate slide mounted thereon and a vertically movable chaser carrying slide mounted on said intermediate slide, a pattern carrying clutch controlled shaft, means for rotating it, means operated by the main slide for controlling. the clutch of said pattern shaft, an axially movable oscillating shaft, means carried by the oscillating shaft and co-operating with the pattern of the pattern carrying shaft for axially moving said oscillating shaft, means for oscillating said shaft, a feed rod tied to said oscillating shaft for horizontally shifting the intermediate slide and thereby the chaser slide, and means carried by the main slide and contacting with the chaser slide for controlling the disengagement of the chaser from the work and comprising a semi-circular cam.

'16. Thread chasing mechanism for automatic lathes comprising a vertically and horizontally movable slide mechanism carrying a chaser, means for shifting a part of the slide mechanism horizontally and comprising a rotary pattern controlled means, and means controlled by the slide mechanism for throwing into operation said slide shifting means.

1'7. Thread chasing mechanism for automatic lathes comprising a .vertically and horizontally movable slide mechanism carrying a chaser, means for shifting the slide mechanism horizontally and comprising a clutch controlled pattern shaft, a clutch shifter, a spring controlled clutch shifter rod co-operating with the slide mechanism and means controlled by the pattern shaft and connected with the slide mechanism, and means controlled by the slide mechanism for throwing into operation said-slide shifting means.

18. Thread chasing mechanism for automatic lathes comprising a vertically and horizontally movable slide mechanism carrying a chaser, means for shifting the slide mechanism horizontally and comprising a clutch controlled, pattern shaft, a clutch shifter, a spring controlled clutch shifter rod co-operating with the slide mechanism and means controlled by the pattern shaft and connected with the slide mechanism and including an oscillating shaft tied' to the means connected with the slide mechanism, and means controlled by the slide mechanism for throwing into operation said slide shifting means.

19. Thread chasing mechanism for automatic lathes, comprising a vertically and horizontallymovable slide mechanism carrying a chaser, means for shifting the slide mechanism horizontally and comprising a clutch controlledpattern shaft, a clutch shifter, a spring controlled clutch shifter rod co-operating with the slide mechanism and means controlled by the pattern shaft and connected with the slide mechanism and including an oscillating shaft tied to the means connected with the slide mechanism, means controlled by the slide mechanism for throwing into operation said slide shifting means, and means for oscillating said shaft.

20. Thread chasing mechanism for automatic lathes comprising a vertically and horizontally movable slide mechanism carrying a chaser. means for shifting the slide mechanism horizontally and comprising a clutch controlled pattern shaft, a clutch shifter, a spring controlled clutch shifter rod co-operating with the slide mechanism and means controlled by the pattern shaft and connected with the slide mechanism and including an oscillating shaft tied to themeans connected with the slide mechanism, means controlled by the slide mechanism for throwing into operation said slide shifting means, and means for oscillating s'aid shaft and comprising cam means and rotary'driving means for the clutch controlled pattern shaft and effective to rotate it at reduced speed relative to the work,

21 Thread chasing mechanism for automatic lathes comprising a vertically and horizontally movable slide mechanism comprising-aseries of three superposed slides carrying a chaser, means 1 for shifting a part of the slide mechanism horizontally and comprising a rotary pattern controlled means, and means controlled by the slide mechanism for throwing into operation said slide shifting means.

RUDOLF ECKARDT.

ERICH HUTH.

r'Rrrz mam.

RICHARD RAHM. 

